Commit e180b8c4 authored by Gao Xiang's avatar Gao Xiang
Browse files

erofs: convert z_erofs_bind_cache() to folios 



The managed cache uses a pseudo inode to keep (necessary) compressed
data.

Currently, it still uses zero-order folios, so this is just a trivial
conversion, except that the use of the pagepool is temporarily dropped.

Drop some obsoleted comments too.

Reviewed-by: default avatarChao Yu <chao@kernel.org>
Signed-off-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20250114034429.431408-4-hsiangkao@linux.alibaba.com
parent 6f435e94

fs/erofs/compress.h

+1 −22
Original line number Diff line number Diff line
@@ -29,29 +29,8 @@ struct z_erofs_decompressor { 
	char *name;

};



/* some special page->private (unsigned long, see below) */

#define Z_EROFS_SHORTLIVED_PAGE		(-1UL << 2)

#define Z_EROFS_PREALLOCATED_PAGE	(-2UL << 2)



/*

 * For all pages in a pcluster, page->private should be one of

 * Type                         Last 2bits      page->private

 * short-lived page             00              Z_EROFS_SHORTLIVED_PAGE

 * preallocated page (tryalloc) 00              Z_EROFS_PREALLOCATED_PAGE

 * cached/managed page          00              pointer to z_erofs_pcluster

 * online page (file-backed,    01/10/11        sub-index << 2 | count

 *              some pages can be used for inplace I/O)

 *

 * page->mapping should be one of

 * Type                 page->mapping

 * short-lived page     NULL

 * preallocated page    NULL

 * cached/managed page  non-NULL or NULL (invalidated/truncated page)

 * online page          non-NULL

 *

 * For all managed pages, PG_private should be set with 1 extra refcount,

 * which is used for page reclaim / migration.

 */

#define Z_EROFS_PREALLOCATED_FOLIO	((void *)(-2UL << 2))



/*

 * Currently, short-lived pages are pages directly from buddy system

fs/erofs/zdata.c

+20 −31
Original line number Diff line number Diff line
@@ -516,13 +516,11 @@ static void z_erofs_bind_cache(struct z_erofs_frontend *fe) 
	struct z_erofs_pcluster *pcl = fe->pcl;

	unsigned int pclusterpages = z_erofs_pclusterpages(pcl);

	bool shouldalloc = z_erofs_should_alloc_cache(fe);

	bool standalone = true;

	/*

	 * optimistic allocation without direct reclaim since inplace I/O

	 * can be used if low memory otherwise.

	 */

	bool may_bypass = true;

	/* Optimistic allocation, as in-place I/O can be used as a fallback */

	gfp_t gfp = (mapping_gfp_mask(mc) & ~__GFP_DIRECT_RECLAIM) |

			__GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN;

	struct folio *folio, *newfolio;

	unsigned int i;



	if (i_blocksize(fe->inode) != PAGE_SIZE ||
@@ -530,47 +528,42 @@ static void z_erofs_bind_cache(struct z_erofs_frontend *fe) 
		return;



	for (i = 0; i < pclusterpages; ++i) {

		struct page *page, *newpage;



		/* Inaccurate check w/o locking to avoid unneeded lookups */

		if (READ_ONCE(pcl->compressed_bvecs[i].page))

			continue;



		page = find_get_page(mc, pcl->index + i);

		if (!page) {

			/* I/O is needed, no possible to decompress directly */

			standalone = false;

		folio = filemap_get_folio(mc, pcl->index + i);

		if (IS_ERR(folio)) {

			may_bypass = false;

			if (!shouldalloc)

				continue;



			/*

			 * Try cached I/O if allocation succeeds or fallback to

			 * in-place I/O instead to avoid any direct reclaim.

			 * Allocate a managed folio for cached I/O, or it may be

			 * then filled with a file-backed folio for in-place I/O

			 */

			newpage = erofs_allocpage(&fe->pagepool, gfp);

			if (!newpage)

			newfolio = filemap_alloc_folio(gfp, 0);

			if (!newfolio)

				continue;

			set_page_private(newpage, Z_EROFS_PREALLOCATED_PAGE);

			newfolio->private = Z_EROFS_PREALLOCATED_FOLIO;

			folio = NULL;

		}

		spin_lock(&pcl->lockref.lock);

		if (!pcl->compressed_bvecs[i].page) {

			pcl->compressed_bvecs[i].page = page ? page : newpage;

			pcl->compressed_bvecs[i].page =

				folio_page(folio ?: newfolio, 0);

			spin_unlock(&pcl->lockref.lock);

			continue;

		}

		spin_unlock(&pcl->lockref.lock);



		if (page)

			put_page(page);

		else if (newpage)

			erofs_pagepool_add(&fe->pagepool, newpage);

		folio_put(folio ?: newfolio);

	}



	/*

	 * don't do inplace I/O if all compressed pages are available in

	 * managed cache since it can be moved to the bypass queue instead.

	 * Don't perform in-place I/O if all compressed pages are available in

	 * the managed cache, as the pcluster can be moved to the bypass queue.

	 */

	if (standalone)

	if (may_bypass)

		fe->mode = Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE;

}
@@ -1480,12 +1473,8 @@ static void z_erofs_fill_bio_vec(struct bio_vec *bvec, 
	DBG_BUGON(z_erofs_is_shortlived_page(bvec->bv_page));



	folio = page_folio(zbv.page);

	/*

	 * Handle preallocated cached folios.  We tried to allocate such folios

	 * without triggering direct reclaim.  If allocation failed, inplace

	 * file-backed folios will be used instead.

	 */

	if (folio->private == (void *)Z_EROFS_PREALLOCATED_PAGE) {

	/* For preallocated managed folios, add them to page cache here */

	if (folio->private == Z_EROFS_PREALLOCATED_FOLIO) {

		tocache = true;

		goto out_tocache;

	}